AirHint found the following cheapest return flights from Seoul (ICN) to Brussels (BRU) in September 2025 (see full year).

Return flights

24 Sep - 01 Oct	China Eastern
24 Sep - 29 Sep	SWISS
23 Sep - 30 Sep	Qatar Airways
24 Sep - 28 Sep	SWISS
29 Sep - 13 Oct	Jeju Air
21 Sep - 01 Oct	Etihad Airways
26 Sep - 11 Oct	Thai AirAsia X
29 Sep - 30 Sep	KLM
29 Sep - 06 Oct	KLM
30 Sep - 06 Oct	LOT
28 Sep - 02 Oct	Cathay Pacific
30 Sep - 07 Oct	Air Canada
21 Sep - 30 Sep	Cathay Pacific
28 Sep - 05 Oct	Etihad Airways
22 Sep - 27 Sep	Lufthansa

Also check the deals for one-way flights from Seoul to Brussels in September.

The deals are updated regularly. The prices may go up as tickets are purchased by other travellers. Only the cheapest flights are offered. Select a price to book and secure these cheap prices.

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Cheapest return flights from Seoul to Brussels in September from $733

Return flights